Everyone knows sweet corn, the vegetable we eat commonly at our meals. We also eat a lot of popcorn--plain, buttered or coated with caramel. Most of us don't know about grain, or field corn. The reality is that we plant almost 68 million acres of corn annually in the United States and almost 88 percent of it is field corn, according to Purdue University. Sweet corn slightly less than 12 percent, and less than 2 percent is planted in popcorn.
Field, or Grain Corn
Purdue University lists four main varieties of grain corn: dent, flint, flour and waxy. Ripe kernels of dent corn have an indentation, or dent at the tops. This is caused by shrinkage of the soft starch at the center of each kernel. Dent corn kernels vary in shape from wide and shallow to long and narrow. Dent corn makes up most of the field corn grown in the United States, according to . Flint corn is similar to dent corn. Soft, or flour corn is almost completely soft starch, with a thin layer of hard starch. Not much flour corn is commercially grown in the United States. Waxy corn has a waxy appearance to its the broken or cut endosperm. Most of the small amount of waxy corn grown is used industrially.
According to the University of Illinois Extension, sweet corn has three main varieties: normal (non-hybrid) sugary (SU), sugary enhanced (SE) and supersweet (Sh2). SU corn varieties have a gene that creates the sweetness and creaminess we associate with sweet corn. The SU qualities are very unstable, so SE varieties were developed. SE corn has much more sugar than SU varieties, but still has the creamy, tender texture of SU sweet corn. Sh2 sweet corn varieties have more sugar than either SU or SE sweet corn. The kernels are very crisp, with tough skin, and don't have the creamy texture and traditional "corny" flavor of SU and SE corn. This particularly affects the quality of frozen and canned Sh2 corn. Sh2 is also more difficult to grow than SU or SE corn. Most table corn grown today is from SE varieties.
In testing, Mercer University found that there are two varieties of popcorn, yellow, or pearls, and white, or rice. Yellow popcorn ranges is rounded in shape and is yellow or orange in color. It has a hull when it is popped. White popcorn, has white kernels that are longer and pointed in shape. It is often referred to as hull-less popcorn, but it does have some hulls when popped.